phosphorus tribromide; 1,5-diazabicyclo[5.4.0]undeca-5-ene 1) THF, Et2O, 1 h, 2) THF, pentane, 20 h; Yield given. Multistep reaction;

1: 1) PBr3, 2) 1,5-diazabicyclo<5.4.0>undec-5-ene / 1) THF, Et2O, 1 h, 2) THF, pentane, 20 h 2: 33 percent / H2O / tetrahydrofuran / 1.5 h View Scheme